The goal of this research project is identification, isolation, and molecular characterization of the beta-adrenergic receptor. This will be accomplished by the use of specific highly radioactive photoaffinity labeling reagents which are derivations of potent beta-antagonists, such as propranolol and pindolol. Purification of the receptor will be attempted using alprenolol affinity columns. Detergent extracts of membranes containing receptor-beta-receptor antagonist (with DNP groups attached) will be passed over the columns to effect purification of the receptor. Other aspects of this proposal involve investigations on the involvement of sulfhydryl groups in the mechanism by which catecholamines activate adenylate cyclase. Distribution of the receptor on the surface of cells will be investigated using bifunctional ligands containing biotin and the protein, avidin, suitably derivatized for microscope visualization.